What is best way to organize a scene with different sets of materials?
Thank you for posting your question so clearly.
Yes, there is a better way to do this, specifically for Archviz.


Create a SPHERE or GRID, apply desired texture material.
On your scene, FIRST select your wall-to-be-changed-material, then select the sphere/grid you created to represent your material LAST. Hit CTRL+L (Link data shortcut) and select MATERIAL.

Now, repeat for all geometry that will use that material. In my example picture, everything in the house that will use the PINK material, are "CTRL+L" (Linked) to that material. 



Have your material nodes ready and separated to connect EACH material into the corresponding "LINKED MATERIAL sphere/grid".
This is how you can change materials amazingly quicker without the need to enter groups. This way you change all your properties visually -by literally interchanging- the material output connector.

Notice the first thing is to link geometry to this other geometry which contains the TEXTURE. (1). Inside that material you have all your OTHER MATERIAL NODE GROUP options. So it is easy for you to single connect (interchange connect) when you touch that material (for the sake of the example: I´m going to call the ball mesh material "GRASS", so I know all GRASS elements are depending (LINKED) to this material. 
Then, on the shader tree, I can have other NODE GROUP options to reconnect other option materials (2).


If asset library was here (Blender 2.8 new feature) we could do just "drag drop" materials on this LINKED mesh. But since we can´t now (feature probably available by May or later), then all we are left to, is to have the group nodes contained INSIDE the material, but not connected until you want to switch them.

Thanks if you vote me up as ANSWER to your question.
Cheers.